First, one can extend X11 fairly easily, this has been done in the past. Second, X11 already has asynchronous IPC.
First, you don't extend X, you work around it and leave one more bit of dead code to be maintained forever. Second, it is not async.
Again: bullshit. X11 can do take advantage of the hardware in exactly the same way as Wayland
Sorry you're lying. X11 has no concept of surfaces. The only way of taking advantage of the hardware is to write an extension that composites the scene for X11 and hands it back to X11 to page flip. So X11 is just a 3rd wheel that involves extra context switches for no reason at all.
I don't want RDP. RDP is not compatible with X. RDP is also a propriertary protocol fron Microsoft with a core standardized by the ITU. I sure hell to not want this as a replacement for X.
Oh boo hoo then implement something else.
Yes, implement X. Then come back.
Run X over wayland if you're so desperate for some crappy broken network protocol. VNC, RDP and others are more efficient.
I am not playing games. I want my new applications to work with old display servers and old applications to work with new servers.
And Wayland stops you how? Run X11 over wayland and stop crying.